
is a solution of Eq. REF . However, \(_{k, B}\)  contains singular points because \(\eta (z)\)  is not an analytical function. The denominator in Eq. REF  vanishes at \(x_0 + m L_1 + n L_2\)  where \(x_0 = - \frac{1}{3} (L_1 + L_2)\) , and \(m\)  and \(n\)  are arbitrary integers, and in general, \(_{k, B}\)  is not normalizable[1]}.
